1. Field of the Invention
The present invention relates to an internal combustion engine intended to reduce the harmful components of exhaust gases by a simplified engine construction and, more particularly, to an improvement in a so-called "torch ignition type internal combustion engine" in which a lean air-fuel mixture in a main combustion chamber is ignited by a torch produced by the ignition of an air-fuel mixture charge in a trap chamber.
2. DESCRIPTION OF THE PRIOR ART
To operate an internal combustion engine with a lean air-fuel mixture is effective to reduce the harmful components of exhaust gases of the engine.
With the conventional internal combustion engine, however, a misfire takes place when the air-fuel mixture charge is as lean as an air-fuel ratio of about 17. Thus, in order to obtain stable combustion of a lean air-fuel mixture in an internal combustion engine, it is necessary to provide the combustion chamber of the engine with some measures.
A torch ignition type internal combustion engine, as is known, has a small combustion chamber and a trap chamber which is in communication therewith by a torch aperture or apertures and in which electrodes of a spark plug are disposeed. The trap chamber is adapted to be supplied with a rich air-fuel mixture which is ignitable by a spark discharge of the spark plug to produce a torch which in turn reliably ignites a lean air-fuel mixture in the main combustion chamber. The known torch ignition type internal combustion engine, however, needs at least two, independent fuel supply circuits, one for supplying the lean air-fuel mixture to the main combustion chamber and the other for supplying the rich air-fuel mixture to the trap chamber. Thus, the fuel supply system of the known engine is complicated in construction compared with an ordinary internal combustion engine.